Zhe-Xi Luo
Zhe-Xi Luo
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Welcome to the dark side
Welcome to the dark side
Randy Landsberg
Randy Landsberg
Karen Kolb Flude
Karen Kolb Flude
Probing early-universe phase transitions with CMB spectral distortions
If a GUT-scale phase transition occured after inflation, large domains in different vacuum states could be produced via the Kibble mechanism. The resulting network of scaling seeds supports horizon-scale density perturbations at all time (as shown in the below cartoon), stirring the baryon-photon plasma, which then generates CMB spectral distortions as the perturbations diffusively damp. […]
Probing a panoply of curvaton-decay scenarios using CMB data
In the curvaton model, an energetically sub-dominant field (the curvaton) during inflation eventually begins to redshift as matter, allowing it and its decay products to later dominate the overall primordial density fluctuation (overtaking that caused by fluctuations in the inflaton itself). In this work, Tristan Smith and I systematically probed and limited the curvaton parameter […]
Search for Compensated Isocurvature Perturbations with Planck Power Spectra
One interesting feature of compensated isocurvature perturbations (CIPs) is that they have a similar effect on CMB power spectra to weak lensing of the CMB. CIPs are fluctuations in the relative number densities of dark matter and baryons. In this work (led by Johns Hopkins graduate student Julian B. Muñoz under my mentorship & supervised […]
Compensated isocurvature perturbations in the curvaton model
Compensated isocurvature perturbations (CIPs) are fluctuations in the relative density of baryons and cold dark matter (CDM) at fixed total matter density, which are detectable using CMB data as a result of a spatially varying sound speed in the baryon-photon plasma. In this work, graduate student Chen He (mentored by me & supervised by Prof. […]
Spectral distortions from the dissipation of tensor perturbations
Acoustic waves generate CMB spectral distortions because the linear superposition of blackbodies seen by electrons as they rescatter CMB photons is not itself a blackbody (see right panel of above figure). Gravitational waves similarly produce CMB spectral distortions due to the induced quadrupole seen by electrons at the surface of last scattering (see left panel […]
Spectral distortions from isocurvature perturbations
Isocurvature perturbations are fluctuations in the relative number densities of particles at constant total density. Like adiabatic (or total density) fluctuations, primordial isocurvature perturbations will excite acoustic waves in the baryon-photon plasma. Jens Chluba and I computed the spectral distortions (deviations of the spatially averaged CMB from a perfect blackbody) generated when these acoustic waves […]
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